Mjor objectives of proposed research are to quantitatively assess factors associated with individual susceptibility to dental caries and periodontal disease. Factors in dental caries will be examined by comparative studies of salivary secretions and plaque in caried resistant and susceptible subjects. Parameters to be examined will include antibody levels aganst specific organisms, inhibitory titers for specific enzymes, peroxidase and aggregation activity. Periodontal disease factors will be studied in a variety of ways: a) comparative studies of saliva and plaque in heavy and light calculus formers, b) nature of subgingival deposits, c) nature and pathogenicity of non-adherent deposits, d) relation of gingival fluid to clinical status, e) antigen penetration of gingival tissues under different clinical conditions. This last study will employ a Veillonella endotoxin as the "tag" and includes fluorescent microscopy and electron microscopy in the surveillance of the marker substance.